JP2024016289A - Iron-based sintered sliding member and its manufacturing method - Google Patents

Abstract

An object of the present invention is to provide an iron-based sintered sliding member that has excellent sliding performance. [Solution] S: 3 to 15%, one or more selected from the group consisting of Cr, Ca, V, Ti, and Mg: 0.2 to 6% in total amount, and the balance: An iron-based sintered sliding member comprising Fe and unavoidable impurities and a base in which sulfide particles containing one or more selected from the group consisting of Cr, Ca, V, Ti, and Mg are dispersed, and pores. is provided. [Selection diagram] Figure 1

Description

One embodiment of the present invention relates to an iron-based sintered sliding member and a method for manufacturing the same.

The so-called powder metallurgy method, in which raw powder is compression-molded in a mold and the resulting green compact is sintered, can be shaped into a near-net shape, so there is less machining allowance during subsequent machining and material loss is small. Moreover, once a mold is made, it is possible to produce a large quantity of products of the same shape, making it highly economical. Furthermore, the powder metallurgy method has a wide range of alloy designs because it allows the production of special alloys that cannot be obtained with alloys produced by ordinary melting. For this reason, it is widely applied to mechanical parts including automobile parts.

Among mechanical parts, it is important for sliding members to have a low coefficient of friction and wear resistance. Particularly in applications where high surface pressure is applied, a sliding member formed of a copper-based sintered body such as bronze-based or lead bronze-based is preferably used.
In conventional copper-based sintered bodies, lubricating oil is retained in the pores included in the sintered bodies, and wear resistance can be improved. Furthermore, in the lead bronze-based sintered body, the lead phase contained in the matrix acts as a solid lubricant and can improve wear resistance.

Patent Document 1 describes an iron-based sintered sliding member that has excellent sliding properties and mechanical strength, and has a metal structure consisting of a ferrite base in which sulfide particles are dispersed and pores. On the other hand, an iron-based sintered sliding member is proposed in which the content is dispersed at 15 to 30% by volume.
Patent Document 1 describes that the sulfide precipitated in the matrix preferably has a predetermined size in order to exhibit a solid lubricating effect. Specifically, Patent Document 1 proposes that the area of sulfide particles having a maximum particle size of 10 μm or more preferably occupies 30% or more of the area of the entire sulfide particles.
Patent Document 2 proposes a machinable sintered member in which MnS particles of 10 μm or less are uniformly dispersed in crystal grains over the entire surface of the base structure, as a sintered member that improves machinability while maintaining strength. Ru.

Japanese Patent Application Publication No. 2014-181381 Japanese Patent Application Publication No. 2002-332552

Since lead bronze sintered bodies contain a large amount of lead, there is a desire to reduce lead and develop alternative materials in order to address environmental issues. Although various materials are being considered as substitute materials for lead bronze-based sintered bodies, further improvements in the coefficient of friction and wear resistance of copper-based sintered bodies are desired. In addition, copper-based sintered bodies use a large amount of copper, resulting in an increase in cost.

From the description in Patent Document 1, in the iron-based sintered sliding member, the particle size of the sulfide particles in the matrix is preferably as large as 10 μm or more from the viewpoint of sliding performance. In Patent Document 1, iron sulfide is added to iron powder containing 0.03 to 0.9 mass% Mn as an unavoidable impurity, so that the sulfide particles are set at a predetermined volume ratio in the sintered body, and Sulfide particles are coarsened.

In Patent Document 2, MnS particles are precipitated in a sintered body by adding MoS ₂ powder to iron powder containing Mn. Mn is a component that is easily oxidized, and it is difficult to manufacture and obtain raw materials for Mn-rich iron alloys.
One embodiment of the present invention aims to provide an iron-based sintered sliding member with excellent sliding performance.

One embodiment of the invention is as follows.
[1] In mass%, S: 3 to 15%, one or more selected from the group consisting of Cr, Ca, V, Ti, and Mg: 0.2 to 6% in total amount, balance: Fe An iron-based sintered sliding member, comprising a base in which sulfide particles containing at least one selected from the group consisting of Cr, Ca, V, Ti, and Mg are dispersed, and pores.
[2] The iron-based sintered sliding member according to [1], further containing 0 to 10% Ni.
[3] The iron-based sintered sliding member according to [1] or [2], further containing Mo: 0 to 10%.
[4] The iron-based sintered sliding member according to any one of [1] to [3], further containing graphite: 0 to 1%.
[5] A sliding component using the iron-based sintered sliding member according to any one of [1] to [4].

[6] Iron alloy powder A containing at least 1% by mass of one or more selected from the group consisting of Cr, Ca, V, Ti, and Mg and sulfur alloy powder B are added to the sulfur of the final sintered body. An iron-based sintered sliding material that is added so that the content is 3 to 15% by mass, compression molds the obtained mixed powder, and sinters the obtained molded body at a temperature range of 900°C to 1200°C. Method of manufacturing parts.
[7] The method for producing an iron-based sintered sliding member according to [6], wherein the mixed powder further contains 3% by mass or more of one or more selected from the group consisting of nickel powder and nickel-iron alloy powder. .
[8] The method for producing an iron-based sintered sliding member according to [6] or [7], wherein the mixed powder further contains graphite in an amount of 0 to 1% by mass.

[9] An iron-based sintered sliding member in which the area ratio of metal sulfide is 20% or more and the number of metal sulfide particles per unit area is 8.0×10 ¹⁰ particles/m ² or more.
[10] The iron-based sintered sliding member according to [9], wherein the number of metal sulfide particles having a particle diameter of 1 μm or less is 40% or more of the total number of metal sulfide particles.
[11] An iron-based material in which the area ratio of metal sulfide is 20% or more, and the number of metal sulfide particles with a particle size of 1 μm or less is 40% or more of the total number of metal sulfide particles. Sintered sliding member.
[12] The iron-based sintered slide according to any one of [9] to [11], wherein the metal sulfide contains one or more selected from the group consisting of CrS, CaS, VS, TiS, and MgS. Element.
[13] A sliding component using the iron-based sintered sliding member according to any one of [9] to [12].

According to one embodiment, an iron-based sintered sliding member with excellent sliding performance can be provided.

FIG. 1 is a graph showing the thrust sliding performance of the example. FIG. 2 is a graph showing the radial sliding performance of the example. FIG. 3 shows a cross-sectional image of the sintered member of Example 1. FIG. 4 shows cross-sectional images of the sintered members of Example 1 and Comparative Example 2.

Hereinafter, one embodiment of the present invention will be described, but the present invention is not limited to the following examples.

The iron-based sintered sliding member according to one embodiment has S: 3 to 15% in mass %, one or more selected from the group consisting of Cr, Ca, V, Ti, and Mg: 0. A base in which sulfide particles containing 2 to 6%, the remainder consisting of Fe and unavoidable impurities, and having one or more selected from the group consisting of Cr, Ca, V, Ti, and Mg are dispersed, and pores. It is characterized by containing.

The iron-based sintered sliding member according to one embodiment is formed of an iron-based sintered body.
The iron-based sintered body contains Fe as a main component. Here, the main component means a component that occupies the majority of the iron-based sintered body. The amount of Fe is preferably 50% by mass or more, more preferably 60% by mass or more with respect to the overall composition of the iron-based sintered body.
The iron-based sintered body can be manufactured by powder metallurgy using raw materials containing iron powder and/or iron alloy powder.
The porosity of the sintered body is preferably 5 to 40%, and the pores may be impregnated with lubricating oil.

A sliding component according to one embodiment is formed using an iron-based sintered sliding member.
The sliding component may be integrally formed of an iron-based sintered body. Moreover, when the sliding component is used in combination with an iron-based sintered body and other members, it is preferable that at least a portion including the sliding surface is formed of the iron-based sintered body.

In the iron-based sintered body, the base preferably contains a metal sulfide.
Examples of metal sulfides include FeS, MnS, CrS, MoS ₂ , VS, etc., or combinations thereof. Preferably, the metal sulfide may include one or more selected from the group consisting of MnS, CrS, and VS. More preferably, the metal sulfide may contain at least one of CrS and VS.
Among these, it is preferable that the iron-based sintered body contains CrS. CrS is derived from the raw material Cr and is blended into the iron-based sintered body, but since Cr is included in the raw material iron powder, CrS is finely dispersed in the matrix in the iron-based sintered body, which is the sintered body. It will be distributed and blended.

Metal sulfides contribute to sliding properties as solid lubricants. In the iron-based sintered body, the area ratio of the metal sulfide to the matrix is preferably 20% or more. Thereby, an appropriate amount of metal sulfide can be exposed on the sliding surface of the sliding member, and sliding performance can be further improved.
In the iron-based sintered body, the area ratio of metal sulfide to the base is preferably 35% or less.

Here, as a method for measuring the area ratio of metal sulfides, for example, an iron-based sintered body is cut at an arbitrary point, an arbitrary point on the cross section is corroded with methanol, and mirror polished to make the metal structure visible. The process is performed by obtaining an elemental analysis image of the processed cross section using an electron beam microanalyzer (for example, "EPMA1600" manufactured by Shimadzu Corporation). The measurement is performed using a wavelength dispersive spectrometer (WDS). The measurement conditions can be, for example, an accelerating voltage of 15 kV, a sample current of 100 nA, a measuring time of 5 m·sec, and an area size of 604×454 μm. Further, the elemental analysis image can be an image with a magnification of 500 times, for example. Metal sulfides are observed in the form of black particles in the matrix. For example, image analysis software (WinROOF manufactured by Mitani Shoji Co., Ltd.) can be used for image analysis.

The iron-based sintered body preferably has 500 or more metal sulfide particles within a region of 84.4 μm x 60.5 μm.
As a result, more fine metal sulfide particles are contained in the base of the iron-based sintered body, and a large number of fine particles can be exposed on the sliding surface of the sliding member, improving sliding performance. It can be further improved.

Here, the number of metal sulfide particles can be determined by, for example, cutting an iron-based sintered body, mirror-polishing the cross section, observing an image of the polished surface, and determining the number of particles contained in an 84.4 μm x 60.5 μm area of the polished surface. It can be determined by measuring the metal sulfide particles contained in the metal sulfide particles. For example, image analysis software (WinROOF manufactured by Mitani Shoji Co., Ltd.) can be used for image analysis.

Preferably, the metal sulfide is finely dispersed. The number of metal sulfide particles per unit area of the iron-based sintered body is preferably 8.0×10 ¹⁰ particles/m ² or more, more preferably 1.0×0 ¹¹ particles/m ² or more.
As a result, more fine metal sulfide particles are contained in the base of the iron-based sintered body, and a large number of fine particles can be exposed on the sliding surface of the sliding member, improving sliding performance. It can be further improved.
The number of metal sulfide particles per unit area of the iron-based sintered body is preferably 1.0×10 ¹² particles/m ² or less.
When the number of metal sulfide particles increases, there is a possibility that a plurality of metal sulfides combine to generate larger particles, so within this range, a large amount of fine particles can be contained more appropriately.

Here, the number of metal sulfide particles per unit area can be determined by, for example, cutting an iron-based sintered body, mirror-polishing the cross section, observing an image of the polished surface, and calculating the number of particles included in a predetermined measurement area of the polished surface. It can be determined by measuring metal sulfide particles. For example, image analysis software (WinROOF manufactured by Mitani Shoji Co., Ltd.) can be used for image analysis.

In the iron-based sintered body, the number of metal sulfide particles having a particle diameter of 1 μm or less is preferably 40% or more, more preferably 50% or more, based on the total number of metal sulfide particles.
As a result, more fine metal sulfide particles are contained in the base of the iron-based sintered body, and a large number of fine particles can be exposed on the sliding surface of the sliding member, improving sliding performance. It can be further improved.
In the iron-based sintered body, the number of metal sulfide particles with a particle size of 1 μm or less may be 100% of the total number of metal sulfide particles, but there is a possibility that coarse particles may be mixed in. Therefore, it may be 90% or less.
Within this range, a large amount of fine particles can be contained more appropriately.

Here, the ratio of the number of metal sulfide particles with a particle size of 1 μm or less can be determined by, for example, cutting an iron-based sintered body, mirror-polishing the cross section, observing an image of the polished surface, and Measure the number of all metal sulfide particles included in an area of size 84.4 μm x 60.5 μm and the number of metal sulfide particles with a particle size of 1 μm or less, and calculate from the ratio of the numbers. Can be done. For example, image analysis software (WinROOF manufactured by Mitani Shoji Co., Ltd.) can be used for image analysis.

The iron-based sintered body contains, in mass%, S: 3 to 15%, one or more selected from the group consisting of Cr, Ca, V, Ti, and Mg: 0.2 to 6% in total amount. , the remainder: preferably consists of Fe and unavoidable impurities.
Furthermore, the iron-based sintered body can further contain Ni: 0 to 10%, Mo: 0 to 10%, graphite: 0 to 1%, or a combination thereof.

The composition of the iron-based sintered body will be explained below.
S: 3-15%
By including S in the iron-based sintered body, metal sulfide can be included in the base. Thereby, an appropriate amount of metal sulfide can be exposed on the sliding surface of the sliding member, and sliding performance can be further improved. S is preferably 0.5% or more, more preferably 1% or more, even more preferably 2% or more, and even more preferably 3% or more.
Excessive S may inhibit sinterability and reduce strength. Furthermore, S may be scattered during sintering. Therefore, S is preferably 15% or less, preferably 6% or less, more preferably 5% or less, and even more preferably 4% or less. In addition, within this range, it is possible to prevent multiple metal sulfide particles from combining to form one large particle, and it is possible to incorporate finer metal sulfide particles into the base, improving sliding performance. It can be further improved.
Sulfur is preferably added as an unstable sulfur alloy powder, such as iron sulfide or _MoS2 .

Cr: 0.2-6%
Generally, the greater the difference in electronegativity from S, the easier it is to form sulfides. The electronegativity value (electronegativity by Pauling) is S: 2.58, Mn: 1.55, Cr: 1.66, Fe: 1.83, Cu: 1.90, Ni: 1.91. , Mo: 2.16, sulfides are likely to be formed in the order of Mn>Cr>Fe>Cu>Ni>Mo. Therefore, sulfur combines with a trace amount of Mn as an impurity contained in the iron powder to produce MnS. Thereafter, a reaction occurs with chromium, and chromium sulfide is precipitated. Chromium has a high melting point, does not agglomerate, and reacts with sulfur when it remains in a dispersed state, making it possible to generate fine metal sulfides in the base. When the Cr content is 0.2% or more, preferably 0.5% or more, and more preferably 1.0% or more, the material strength can be increased and the sliding performance can be improved. Cr is preferably 6% or less.

The same phenomenon as with Cr occurs with Ca, V, Ti, and Mg, and fine metal sulfides can be generated in the base. Ca, V, Ti, and Mg are each independently preferably 0.1 to 6.0%, more preferably 0.2 to 6%, and even more preferably 0.2 to 4%. Further, the total amount of Cr, Ca, V, Ti, and Mg is preferably 0.2 to 6%, more preferably 0.2 to 4%.

Mn: 0-0.5%
Mn exists in iron powder as an inevitable impurity. Mn is also a component that is easily oxidized, making it difficult to produce a manganese-rich iron-manganese alloy. Although manganese-rich iron-manganese alloys exist, they are expensive.
Mn can generate fine metal sulfides in the matrix, but there is an upper limit to the amount of manganese in the iron-manganese alloy of raw material powder that provides manganese, and there is also a limit to the amount of metal sulfides that can be formed in the sintered body. There is an upper limit. Mn is preferably 0 to 0.5%.

Mo: 0~10%
Mo has the effect of promoting sintering, stabilizes the metal structure, especially the ferrite phase, and provides a strong sintered body.
Mo is preferably 0.1% or more, more preferably 1% or more, so that the material strength can be increased and the sliding performance can be improved. Mo is preferably 10% or less.
Mo can be added as Mo powder and/or Mo alloy powder.

Ni: 0-10%
Ni has the function of improving the hardenability of the iron-based sintered body, causing the iron-based sintered body to contain a hardened structure and remaining as austenite after sintering and cooling. Furthermore, due to its electronegativity, Ni does not inhibit the formation of metal sulfides mainly composed of iron sulfide. When Ni is used in combination with C, it improves the hardenability of the iron base, makes pearlite finer and increases its strength, and can obtain high strength bainite and martensite at the normal cooling rate during sintering. It can be easily done.
When the Ni content is 0.1% or more, preferably 0.5% or more, and more preferably 1.0% or more, the material strength can be increased and the sliding performance can be improved. Ni is preferably 10% or less, more preferably 8% or less.
Ni can be added as Ni powder and/or Ni alloy powder.

C: 0-1%
Although C is not an essential element, when 0 to 1% of C is added, a part of C is dissolved in Fe and the strength can be improved.

The remainder of the iron-based sintered material is Fe and may contain unavoidable impurities.
The iron-based sintered material may further include one or more selected from the group consisting of minerals, oxides, nitrides, and borides that do not diffuse into the matrix. These additives include, for example, MgO, _SiO2 , TiN, _CaAlSiO3 , _CrB2, etc., or combinations thereof.

The base of the iron-based sintered body preferably contains one or more types selected from the group consisting of ferrite, pearlite, and martensite as a metal structure. More preferred is a metal structure in which ferrite is the main component.
Preferably, the base has metal sulfides dispersed therein. It is further preferred that the metal sulfide is finely dispersed.

Hereinafter, a method for manufacturing an iron-based sintered sliding member will be described. Note that the iron-based sintered sliding member according to one embodiment is not limited to that manufactured by the following manufacturing method.
A method for manufacturing an iron-based sintered sliding member according to one embodiment includes iron alloy powder containing a total amount of 1% by mass or more of one or more selected from the group consisting of Cr, Ca, V, Ti, and Mg. Sulfur alloy powder B is added to A so that the sulfur content of the final sintered body is 3 to 15% by mass, the obtained mixed powder is compression molded, and the obtained compact is heated at 900°C to 1200°C. This method involves sintering in a temperature range of

It is preferable that Cr, Ca, V, Ti, and Mg are each independently contained in an amount of 0.1 to 8% by mass based on the total amount of the iron alloy powder. The total amount of Cr, Ca, V, Ti, and Mg is preferably 1% by mass or more based on the total amount of the iron alloy powder. Further, it is preferable that the sulfur alloy powder is added to the mixed powder so that the sulfur content of the final sintered body is 3 to 15% by mass. When iron sulfide is used as the sulfur alloy powder, iron sulfide containing 35% by mass or more of S is preferable.

According to this manufacturing method, iron alloy powder A and sulfur alloy powder B, which is a source of S, are separately added to the raw material powder, so that the sulfur alloy powder decomposes and is released during sintering. and one or more selected from the group consisting of Cr, Ca, V, Ti, and Mg in the base can be combined to precipitate MnS, CrS, VS, or a combination thereof. According to such a manufacturing method, MnS, CrS, VS, or a combination thereof can be precipitated in the form of fine particles within crystal grains.

The green compact is preferably sintered so that the maximum holding temperature is 900°C to 1200°C.
By being at a temperature in this range, the sulfur alloy powder decomposes and combines S with one or more selected from the group consisting of Cr, Ca, V, Ti, and Mg in the base to form fine metal particles. Can form sulfides. In addition, it promotes the diffusion of C, Ni, Mn, Cr, Cu, Mo, V, etc. into Fe to generate a metal structure with high base hardness, further increasing the tensile strength of the iron-based sintered body. be able to.
The green compact is preferably held at the maximum holding temperature for 10 to 90 minutes.

Additionally, if a large amount of oxygen is included in the sintering atmosphere, S decomposed from the metal sulfide will combine with oxygen and leave as _SOx gas, reducing the amount of S that combines with the base metal. or sintering in a non-oxidizing atmosphere. As the non-oxidizing atmosphere, for example, decomposed ammonia gas, nitrogen gas, hydrogen gas, argon gas, etc. having a dew point of −10° C. or lower can be used.

After sintering, the sintered body is preferably cooled at a cooling rate of 2° C./min to 400° C./min. More preferably, the temperature is 5 to 150°C. It is preferable to cool the temperature range from the maximum holding temperature to 900 to 200° C. at this cooling rate.

It is preferable that the iron alloy powder contains one or more selected from the group consisting of Cr, Ca, V, Ti, and Mg together with Fe as a main component. The total amount of one or more selected from the group consisting of Cr, Ca, V, Ti, and Mg is preferably 1% by mass or more based on the total amount of iron powder.
The iron alloy powder may further include C, Ni, Cu, Mo or a combination thereof. It is preferable to adjust the blending amount of these elements so as to satisfy the overall composition range of the iron-based sintered body described above.

S is preferably added as a sulfur alloy powder, such as iron sulfide powder or molybdenum disulfide powder.
S has a slow combining power at room temperature, but is extremely reactive at high temperatures, and combines not only with metals but also with nonmetallic elements such as H, O, and C. By the way, in the production of a sintered body, a forming lubricant is generally added to the raw material powder, and the forming lubricant is volatilized and removed during the temperature raising process of the sintering process, which is called dewaxing. When S is applied in the form of sulfur powder, the molding lubricant decomposes and combines with components (mainly H, O, and C) that are generated and is released, thereby stabilizing the S necessary for metal sulfide formation. Difficult to give. When S is applied in the form of sulfur alloy powder, it exists in the form of iron sulfide in the temperature range where the dewaxing process is carried out (approximately 200 to 400 degrees Celsius), so it is mixed with the components produced by decomposition of the forming lubricant. Since S does not separate and S does not separate, S necessary for metal sulfide formation can be stably provided.

When the temperature exceeds 988° C. during the sintering process, a eutectic liquid phase of the sulfur alloy is generated, resulting in liquid phase sintering, which further promotes the growth of necks between powder particles. Further, since S is uniformly diffused into the iron matrix from this eutectic liquid phase, metal sulfide particles can be more uniformly dispersed and precipitated in the matrix. In addition, since the raw material iron alloy powder contains one or more selected from the group consisting of Cr, Ca, V, Ti, and Mg, these elements in the matrix react with S, resulting in finer particles. Metal sulfides can be produced.

The raw material mixed powder may further include nickel powder, nickel-iron alloy powder, or a combination thereof.
Nickel can be preferably used because it forms a solid solution as Ni in the base of the iron-based sintered body and acts to increase the strength of the base. Nickel may be added alone or as an alloy. Nickel can be added in an amount of 3% by mass or more, preferably 5% by mass or more, based on the total amount of the mixed powder.

The mixed powder may further contain graphite in an amount of 0 to 1% by mass. The mixed powder may further contain Mo in an amount of 0 to 10% by mass. The mixed powder may further contain optional components such as a mold lubricant.

Other embodiments of the iron-based sintered sliding member will be described below.
In the iron-based sintered sliding member according to another embodiment, the area ratio of metal sulfide is 20% or more, and the number of metal sulfide particles per unit area is 8.0×10 ¹⁰ particles/m ² or more. characterized by something.
In the iron-based sintered sliding member according to another embodiment, the area ratio of metal sulfide is 20% or more, and the metal sulfide particles have a particle size of 1 μm or less with respect to the total number of metal sulfide particles. It is characterized in that the number of the particles is 40% or more.
According to this, the sliding performance of the sliding member can be improved using the iron-based sintered body.

The iron-based sintered sliding member according to the above other embodiment has a large area ratio of sulfide and a large number of sulfide particles per unit area, so that the metal sulfide contained in the base becomes fine and the sliding member becomes difficult to slide. Performance can be improved.
The iron-based sintered sliding member according to the above-mentioned still other embodiment has a large area ratio of sulfide and a large proportion of the particle size of metal sulfide having a particle size of 1 μm or less. Objects become finer and sliding performance can be improved.

The iron-based sintered body according to the embodiment described above preferably includes pores derived from raw materials such as iron powder as well as a base containing metal sulfide. When lubricating oil is applied to the sliding member and used, the lubricating oil is retained by the pores, and the sliding performance can be further improved over a long period of time.

The iron-based sintered sliding member according to the embodiment described above is obtained by adding sulfur alloy powder to iron alloy powder containing one or more selected from the group consisting of Cr, Ca, V, Ti, and Mg. By compression molding the mixed powder and sintering the obtained molded body, it is possible to form a sintered body with metal sulfide finely dispersed within the crystals.

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to these Examples.

"Manufacturing example 1"
(Example 1)
Raw material powder A Iron alloy powder with a mass ratio of 3% Cr, 0.5% Mo, 0.5% V, and the balance iron Raw material powder B Iron sulfide with a mass ratio of 35% S Raw material powder C Ni powder 10% by mass ratio Powder B, 5% by mass of powder C, and the remainder powder A were mixed to obtain a raw material powder.
Then, the raw material powder was molded at a molding pressure of 600 MPa to produce a ring-shaped green compact. Next, the sintered member of Example 1 was produced by sintering at 1130° C. in a non-oxidizing gas atmosphere.

The sintered member was cut and the chemical composition of the matrix in the cross section was analyzed. The results are shown in Table 1.

The area ratio of metal sulfides in the sintered member was determined by cutting the obtained sample, mirror-polishing the cross section, observing the cross section, and removing pores using image analysis software (WinROOF manufactured by Mitani Shoji Co., Ltd.). The area of the base portion and the area of the metal sulfide were measured, and the area was determined from the area (%) of the metal sulfide in the area of the base. The measurement area was 84.4 μm×60.5 μm.
Metal sulfides were observed in the form of black particles in the base during cross-sectional observation.
The number of metal sulfide particles within a region of 84.4 μm x 60.5 μm was determined by observing the cross section of the sintered member and performing image analysis in the same manner as the area ratio. Then, the number of metal particles per unit area was calculated.
The number of metal sulfide particles having a particle diameter of 1 μm or less with respect to the total number of metal sulfide particles was determined by observing and image analyzing the cross section of the sintered member in the same manner as the area ratio.
The maximum particle diameter of each metal sulfide particle was determined by determining the area of each particle and measuring the equivalent circle diameter, which is converted to the diameter of a circle equal to this area. In addition, when a plurality of metal sulfide particles were combined, the combined metal sulfide was regarded as one metal sulfide, and the equivalent circle diameter was determined from the area of this metal sulfide.
The results are shown in Table 2.

(Comparative example 1)
A ring-shaped compact was produced in the same manner as in Example 1, except that a mixed powder called LBC3 according to the JIS standard was used, and was sintered at 800°C in a non-oxidizing gas atmosphere to obtain the sintering method of Comparative Example 1. A binding member was prepared.
In the same manner as in Example 1, the chemical composition of the matrix of the sintered member was measured. The results are shown in Table 1.

(evaluation)
Sintered members having the following dimensions were produced in the same manner as above, and the following evaluations were performed.
"Thrust sliding performance"
A disk-shaped sintered member with a diameter of 35 mm and a thickness of 5 mm was prepared.
A ring-shaped mating material made of FSD and having an outer diameter of 25 mm, an inner diameter of 24 mm, and a thickness of 15 mm was prepared.
A sliding test was conducted using a ring-on-disk friction and wear tester under the following conditions, and the friction coefficient was measured.
Circumferential speed: 0.5m/sec
Surface pressure: 1, 2,..., 20MPa
Time: 5 min for each surface pressure
Oil type: Oil VG460 (dripping)

In addition, the wear amount (μm) of the disk and ring (FCD) before and after the test was measured.
The results are shown in Figure 1. From FIG. 1, the sintered member of Example 1 had a friction coefficient as low as or lower than that of Comparative Example 1, and the sliding performance was improved. Further, by using the sintered member of Example 1, the amount of wear of the sintered member and the mating material could be reduced.

"Radial sliding performance"
A ring-shaped sintered member with an outer diameter of 16 mm, an inner diameter of 10 mm, and a thickness of 10 mm was prepared.
A shaft made of S45C with a diameter of 9.980 mm and a length of 80 mm was prepared.
A radial crushing test was conducted under the following conditions, and the friction coefficient was measured.
Circumferential speed: 1.57m/min
Surface pressure: 1, 2,..., 80MPa
Time: 5 min for each surface pressure
Oil type: Oil VG460 (impregnated)

In addition, the wear amount (μm) of the ring before and after the test was measured.
The results are shown in Figure 2. From FIG. 2, the sintered member of Example 1 had a friction coefficient as low as or lower than that of Comparative Example 1, and the sliding performance was improved. Further, by using the sintered member of Example 1, the amount of wear of the sintered member could be reduced.

FIG. 3 shows the metal structure (mirror polishing) of the sintered member of Example 1. The iron matrix is the white part, the metal sulfide particles are the gray part, and the pores are the black part.
From FIG. 3, it is observed that metal sulfide particles (gray) are precipitated and finely dispersed in the iron matrix (white).

(Comparative example 2)
Raw material powders were obtained by mixing each raw material so as to have the chemical composition shown in Table 1. A ring-shaped green compact was produced in the same manner as in Example 1, and sintered at 1130° C. in a non-oxidizing gas atmosphere to produce a sintered member of Comparative Example 2.
In the same manner as in Example 1, the chemical composition and physical properties of the base of the sintered member were measured. The results are shown in Tables 1 and 2.

FIG. 4 shows a comparison of the metal structures (mirror polishing) of the sintered members of Example 1 and Comparative Example 2. The iron matrix is the white part, the metal sulfide particles are the gray part, and the pores are the black part.
From FIG. 4, it is observed that, compared to Comparative Example 2, the metal sulfide particles (gray) of Example 1 were precipitated and finely dispersed in the iron base (white).

“Manufacturing example 2”
Raw material powders shown in Table 3 were prepared.
The raw material powders shown in Table 3 were mixed in the combinations shown in Table 4. The blending ratio of each raw material powder was adjusted to obtain the base composition shown in Table 4.
A powder compact was produced in the same manner as in Production Example 1 above, and a sintered member was produced using this.
In Example 10, a sintered member was produced in the same manner as in Comparative Example 1 described above using a mixed powder called LBC3 based on the JIS standard.

For the sintered member, the area ratio of metal sulfide, the number of metal sulfide particles per unit area, the number of metal sulfide particles with a particle size of 1 μm or less relative to the total number of metal sulfide particles, It was measured in the same manner as in Production Example 1 above.
Further, the thrust sliding performance and radial sliding performance of the sintered member were evaluated in the same manner as in Manufacturing Example 1 above. In the evaluation of thrust sliding performance, the amount of thrust wear (μm) was determined from the amount of wear of the disk before and after the test. In the evaluation of radial sliding performance, the amount of radial wear (μm) was determined from the amount of ring wear before and after the test.
The results are shown in Table 5.

Claims (13)

In mass%, S: 3 to 15%, one or more selected from the group consisting of Cr, Ca, V, Ti, and Mg: 0.2 to 6% in total amount, remainder: Fe and inevitable impurities. An iron-based sintered sliding member comprising a base in which sulfide particles containing one or more selected from the group consisting of Cr, Ca, V, Ti, and Mg are dispersed, and pores. The iron-based sintered sliding member according to claim 1, further comprising 0 to 10% Ni. The iron-based sintered sliding member according to claim 1 or 2, further comprising Mo: 0 to 10%. The iron-based sintered sliding member according to any one of claims 1 to 3, further comprising graphite: 0 to 1%. A sliding component using the iron-based sintered sliding member according to any one of claims 1 to 4. Sulfur alloy powder B is added to iron alloy powder A containing one or more selected from the group consisting of Cr, Ca, V, Ti, and Mg in a total amount of 1% by mass or more, so that the sulfur content of the final sintered body is Production of an iron-based sintered sliding member by adding 3 to 15% by mass, compression molding the obtained mixed powder, and sintering the obtained molded body at a temperature range of 900°C to 1200°C. Method. The method for manufacturing an iron-based sintered sliding member according to claim 6, wherein the mixed powder further contains 3% by mass or more of one or more selected from the group consisting of nickel powder and nickel-iron alloy powder. The method for producing an iron-based sintered sliding member according to claim 6 or 7, wherein the mixed powder further contains graphite in an amount of 0 to 1% by mass. An iron-based sintered sliding member in which the area ratio of metal sulfide is 20% or more and the number of metal sulfide particles per unit area is 8.0×10 ¹⁰ particles/m ² or more. The iron-based sintered sliding member according to claim 9, wherein the number of metal sulfide particles having a particle diameter of 1 μm or less is 40% or more of the total number of metal sulfide particles. An iron-based sintered slide in which the area ratio of metal sulfide is 20% or more, and the number of metal sulfide particles with a particle size of 1 μm or less is 40% or more of the total number of metal sulfide particles. moving parts. The iron-based sintered sliding member according to any one of claims 9 to 11, wherein the metal sulfide contains one or more selected from the group consisting of CrS, CaS, VS, TiS, and MgS. A sliding component using the iron-based sintered sliding member according to any one of claims 9 to 12.